As my hex dump showed, and @Ramhound suggested, McAfee Endpoint Encryption did in fact encrypt my drive.
This resulted in a VHD file with:
- McAfee Encryption
- BitLocker Encryption
- Data
- BitLocker Encryption
So when I mounted my VHD on a computer without McAfee Encryption, it sees it as RAW data. Unfortunately, the Endpoint Encryption is specific to the laptop it was installed on. This basically makes my VHD unreadable for any other computer.
The good news is I was able to mount the VHD on the original computer, enter my BitLocker password, and retrieve my data.
I am guessing that the VHD is seen as a local drive, and McAfee policies were probably set to encrypt all local drives.
Basically, don't use VHD + BitLocker on systems that have policies that will automatically encrypt local drives. I have not had this same problem with drives that I completely encrypt with BitLocker, probably because McAfee sees this as an external drive.
I have had no issues using VeraCrypt (or TrueCrypt previously) alongside McAfee - it does not automatically encrypt those containers.